1. Field:
The subject invention is in the field of apparatus for protecting horses hooves and for avoiding or ameliorating harm done to the hooves and other parts of the animal by contacts of the hooves on terrain. On a corollary basis, the invention is in the field of hoofwear provided for the purpose of improving performance of horses in terms of running speed, jumping capability and the like.
2. Prior Art:
Prior art in this field includes that shown in U.S. Pat. Nos.:
3,180,421 PA1 3,921,721 PA1 4,189,004 PA1 4,206,811 PA1 4,496,002 PA1 4,299,288 PA1 4,333,532 PA1 4,420,046
British Pat. No. 565,723 discloses structural forms bearing similarities to structural features of embodiments of the subject invention.
Close prior art is disclosed in U.S. patent application Ser. No. 010,552 filed 2/3/87 by the present inventors and titled Shock Relieving Horseshoe.
Also, in the book entitled "The World Almanac Book of Inventions" by Valerie-Anne Giscard d'Estaing, distributed in the United States by Ballantine Books, on page 139 there is an illustration of a horse fitted with air-cushioned shoes, said to enable the horse to jump even on very hard pavement.
U.S. Pat. No. 4,496,002 covers a horseshoe made of ultra-high molecular weight polyethylene plastic. This patent clearly documents the relationship between lameness in horse's legs and the shocks applied to them by the horse's hooves, citing as a reference "Foreleg Fatigue Fracture," Cheney, J. A.; Lion, S. Y.; Shen, C. K. and Wheat, J. D., Thoroughbred of California, November 1971.
The horseshoe of U.S. Pat. No. 4,496,002 provides some shock relief because of the material from which it is made. It also offers relief by not restricting the natural action of the hoof. It is well known that the natural action reduces the shocks and the lameness attributed to them. This patent cites a comprehensive study of the structure and behavior of horses' feet in action, to be found in the August 1977 issue of Saddle Action, published by Saddle Action, Inc., Paso Robles, Calif., pages 18-21, 50, written by K. D. Butler, Jr. It is stated in the patent that in order for the hoof to function optimally as an absorber, the lower surface of the hoof should have a specific contour. It can be concluded that the proper contour would be produced by normal wear of an unshod hoof of a feral animal.
U.S. Pat. No. 4,333,532 covers a horseshoe devised specifically to facilitate the natural shock absorbing characteristics of horse's hooves, while providing protection and traction for the hooves.
It is well known that in any instance in which a shock is absorbed the energy involved is either converted to heat or stored by some form of energy storage apparatus or some combination of the two. Stored energy is returned and may do useful work when and if the force involved in the action is decreased. Energy converted to heat constitutes a loss of some of the energy being expended for whatever purpose and tends to defeat the purpose of the energy expenditure. In the case of a horse, the energy loss can be manifested in the form of decreased stamina (increased fatigue).
In view of the above discussion it can be concluded that there is a long standing need to shoe horses with apparatus which minimizes, as much as possible by shock relief, the tendency for contacts of the hooves with terrain to produce lameness and other ill effects. At the same time, there are advantages to be gained if the shock relief is accomplished with minimal associated effects such as decrease in stamina due to lost energy. Therefore it is a prime objective of the subject invention to provide hoof wear for a horse which efficiently relieves the shocks on horse's hooves fitted with the hoof wear, the efficiency deriving from the characteristic that the hoof wear stores and returns considerably more of the energy than it converts to heat. Since the efficiency of the natural shock relief of horses' hooves is not generally known and may not be high, it is a further objective of the subject invention to provide efficient shock relief without significant dependence on the hoof's natural shock relief characteristics but without interfering with the natural shock relief to any significant degree. Further objectives are that the hoof wear, which may be termed a horseshoe, have a weight which is in the range of weights for more conventional horseshoes and be fittable and attachable using well known farrier apparatus and techniques. It is a specific objective that the horseshoe weigh no more than 16 ounces and preferably less than 10 ounces. Further, it is an objective that the shoe be no higher than 1.75 inches with a height of less than 1.5 inches preferred. Another objective is that the horseshoe not be adversely affected by use in mud, gravel and the like. Still further objectives are that the horseshoe be durable by conventional standards and suitably economical to manufacture and use.